Bomb fuse



H. H. MOORE April 25, 1950 BOMB FUSE 2 Sheets-Sheet 1 Filed 001'.. 8, 1941 INVENTOR A RNEY H. H. MOORE April 25, 1950 BOMB FUSE 2 Sheets-Sheet 2 Filed Oct. 8, 1941 A winni ATT NEY Patented Apr. 25, 1950 *n UNITED STATES -PATENT OFFICE BOMB FUSE Harry H. Moore, Washington, D. C. l.Application October 8, 1941, Serial No. l114,119 11 claims. (o1. 1oz- 70) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) This invention relates broadly to bombs and more particularly to an improved arming and firing mechanism for the type of depth bomb adapted to be discharged from a Y gun or dropped from an aircraft. This invention also relates to anY arming andring mechanism which would be suitable for use with aerial bombs, supplementing the inertia firing mechanisms usually provided, to give underwater detonation.

It is an o-bject of this invention, therefore, to provide an improved depth bomb, the detonation of which is initiated by the hydrostatic forces which act thereon after the bomb has penetrated a fluid to a predetermined depth.

It is also an object to provide an improved fuse which may be used in a conventional aerial bomb, whereby upon impact with a fluid surface the bomb will penetrate the fluid to a predetermined depth before its detonation is initiated.

It is also another object of this invention to provide an improved hydrostatic fuse for a depth bomb which prevents the possibility of premature detonation which may be produced either as a result of the high inertia forces set up in the bomb upon impact, or as a result of 'the hydrodynamic forces which act upon the fuse when the said bomb is penetrating a uid at a relatively high velocity.

It is a further object of this invention to provide the firing mechanism of an aircraft depth bomb with an interlocking safety mechanism which must be operated upon before the firing mechanism is armed. This interlocking mechanism involves the proper positioning of a booster charge to bring a primer into alignment with its ring pin and to bring a detonator into ignition conductive relationship with said primer and booster charge.

It is a further object of this invention to provide in a ring mechanism for a depth bomb, the detonation of which is initiated by a springactuated firing pin, a new and improved method of releasing the said firing pin by the combined action of two hydrostatic pressure-sensitive devices, each of which must move a predetermined distance in opposite directions.

It is a still further object of this invention to provide a hydrostatic arming and firing mechanism for an aircraft depth bomb with a baille arrangement positioned at the fluid entrance to each hydrostatic sensitive element so that upon impact there will be no Ydirect application Vof the hydrodynamic forces upon the sensitive elements.

Another object of this invention is to provide a fuse having two hydrostats positioned one at each end of the body with an equalizing tube connecting the respective passages leading to each hydrostat, so that unequal hydrodynamic and hydrostatic forces acting on diiferent portions of the bomb will be equalized when acting upon the hydrostats.

It is still another object of this invention to provide a new and' improved lock adapted for use with an aircraft depth bomb, which will maintain the arming and ring mechanism thereof in an immovable, unarmed position so long as the bomb is retained by the aircraft, and which will automatically unlock said arming and firing mechanism, allowing the same to operate, upon the release of the bomb from said aircraft, whereby the arming and ring mechanism will be free to function as a result of the actuation of the hydrostats.

It is another object of this invention to provide an improved depth setting device for a depth bomb adapted to be dropped from an aircraft, said setting device being capable of adjustment after the bomb is placed in the bombrack prior to leaving the ground.

When a depth bomb is dropped from an aircraft at either a high or low altitude the impact with the surface of the water, or the penetration through the water, will set up dynamic pressures and forces of great magnitudes. These forces could cause a premature detonation when acting upon the movable members of prior art hydrostatic pressure sensitive fuses. Various provisions have been made for safeguarding against such premature detonation, including the use of a plurality of hydrostatic diaphragms or pistons which are usually set to operate at different depths. This invention aims to improve upon these prior art provisions in order to simplify their structure, make their operation more positive, more exact, and to make their safety provisions more reliable.

The significant feature of this invention, which tends to prevent a premature detonation, resides in the improved means for releasing the ring pin in response to the movement of the two hydrostats in opposite directions along a common axis. If, however, a bomb containing a. fuse constructed in accordance with the significant feature of this invention should strike the water moving in a directionalong the axis of the fuse, a dynamic pressure would be produced at that end of the fuse receiving the impact tending to Amove the hydrostat inwardly along the said axis,

and inertia forces set up as a result of the impact would act upon the movable members, including the hydrostat positioned at the opposite end, tending to move it inwardly along said axis. Such a coincidence of circumstances would probably cause premature detonation, and it is to obviate such behavior from arising as a result of such possible circumstances that baille plates are provided at the iiuid entrance to each hydrostat.

It is further conceivable that as a result of certain other circumstances the motion of the bomb through the water may not be in the expected axial direction and the pressure at`one end might be different from the pressure atthe.

other end. In anticipation of such circumstances, equalizing tubes are provided which connect the passages leading to the hydrostats at each end of the fuse to equalize the pressure acting thereon.

Additional features and other objects of this invention will become apparent when considered inreierence to the construction, combination and arrangement of parts hereinafter described and illustrated in the accompanying drawing, in which:

Fig. 1 is a horizontal cross-sectional View of an aircraft bomb of the demolition type showing a longitudinal sectional View.V of the hydrostatic fuse, the section through the fuse being taken substantially on line i-l of Fig. 4.

Fig. 2 is a View similar tov Fig. 1, showing the baifle plates and equalizing tubes, and illustrating the preliminary movement-of parts necessary to arm the fuse but insufficient to initiate its ignition.

Fig. 3 is a transverse sectional view through the detonator and primer carrier taken substantially online 3--3 of Fig. 1.

Fig. 4 is a sectional view taken on line -ll of Fig. 2, showing the baille cap, ,the jump out pin and arming wire in detail.

Fig. 5v is a longitudinal sectional view through a modication having an adjustable depth setting mechanism; and

Fig. 6 is an end elevation of a fuse with an adjustable depth setting mechanism illustrated in Fig. 5.l Y

Referring-now to the drawing, and particularly to the modification illustratedr by Figs. 1 to 4 inclusive, the bomb casing adapted to receive the particular fuse constructed in accordance with this invention is indicated generally at it in the drawings. It will be understood from these drawings that the bomb casing is generally cylindrical and is lled with a charge of high explosive (preferably TNT). The fuse is shown mounted diametrically of this casing and with a hydrostat located at each end thereof. The rst hydrostat is indicated in its entirety by the reference numeral 2!) while the second hydrostat is indicated generally by reference numeral S.

The rst hydrostat 2li, as illustrated, includes a piston it movable within a cylindrical casing l 2, which forms the body of the fuse. A cylindrical bellows-shaped member I3, commonly referred to in this art as a Sylphon, is brazed or otherwisev i header lli and end cap 3d so that the entire unit which is hereinafter referred to as the booster extender mechanism will be slidable within the body portion l2 of said fuse.

The movement of the hydrostat 2! is opposed by the stress of a compressed coiled spring 23 as well as the natural resiliency of the Syiphon i3. The spring 23, which is concentric with the bolt 2i, is positioned about a movable sleeve 2li and eng-ages a flange 25 formed on said sleeve at one end thereof. In order for the spring to be compressed upon the axial inward movement of said hydrostat, it isy essential that the sleeve 24 be locked' to the bolt 2|. To accomplish this purpose-the' lock balls 3l) are positioned within the apertures 29 formed within said sleeve and forced into.'v engagement with the grooved portion 33 of the shaft 2l by a` retaining sleeve rihis retainingr sleeveiorms a slidable bearing surface for the movable sleeve 2e and also has a iiange 2l. formed. integrally at an end thereof, opposite the iiange 25, so that the.l spring 23 will be compressed therebetweenr upon the inward movenient of said movable sleeve 2t.

In order to holdthe sleeve 26 in a secured stationary position relative tothe bomb casing an inwardly extendingy collar 32 is formed integrally with the end cap 34 and is pressed about the periphery of the flangedportion 21 of the retaining sleeve 2K6, as clearly illustrated in Figs. l and 2. An annular projection 28 extends axially from flange 2 of the retaining sleeve 26. The inner diameter of this annular projection is greater than the inner diameter of said sleeve so that a void space is formed. around the movable sleeve 2li to serve as apocket for the lock balls 3 when the apertures 29- are in alignment therewith.

The radius of the balls 3i). are preferably greater than the depth of the groove 33 so that the forces transmitted by the bolt 2| through the edge of the. groove to the balls 3G, to the movable sleeve 34 andl to they spring 23, or vice versa, have an outwardly'direoted. radial component which forces the balls out ci the groove and into the pocket formed by the annular projection 28. When-the balls Sil are thusforced into this pocket by the combined. actionof spring 23 and the bolt 2l, thev bolt will then be suddenly Vreleased from its locked engagement with. the movable sleeve 20;., with the result. that the hydrostat 2e will be free to move within the shell i5 without the opposing fcrces of the compressed. coiled spring 23.

In order to permit the fluid upon which the bomb impacts to gain access into the interior of said Sylphon so thatthe fluid pressure may force the hydrostatic piston liv inwardlyfrom its positionA illustrated in Fig. 1 to the position illustrated in Fig. 2.,.a number of axial openings 22 constituting entrance passages are bored into the end cap 3Q. A baille plate 36. is disposed over these openings so that the plurality of transverse passages 69, each of which communicate with a radially extending passage i9 will be in alignment with the axial openings 22, as is clearly illustrated in Figs. 2 and 4. This bale is secured. to the end cap eiland header Hl by means of suitable bolts 35.

A locking member in the form of a spring influenced jump out pin 3d holds the booster extender mechanism in its unextended position illustrated in Fig- 1. The operative features of the locking means are clearly shown in Fig. 4 and include a collar 58 through which an end of the bolt 2l extends. place by the baille plate 36.

This collar is held in The extended end.

of the bolt is provided with a bore 3l which is radially and axially aligned with a bore 49 formed in the baiile plate. The jump out pin 39 is retained in place against the force of the spring 66 by means of either the cotter pin 'I3 or the arming wire la. After the bomb has been secured to the bomb rack one end of the arming wire I4 is inserted and the cotter pin 'i3 is withdrawn in order to arm the bomb rack.

At the inner end of the booster extender mechanism a truncated conical cam member 37 is secured to the booster shell l5. The inner surface of this cam is adapted to engage the outer surface of two slider members 4l and 42 which are supported in a conical retaining block lil and retained in a position outwardly spaced from each other by means of the coiled springs 38. These two slidable members when moved toward each other against the action of the slider springs 38 bring the percussion cap 40, its ignition conduct-ive passage i3 and the mercury fulminate detonator le into axial alignment and ignition conductive relationship with each other and with the projecting ignition transmission train I8 of the sub-booster charge Il. Furthermore movement of the primer slider 4| will also bring the percussion cap 4i! into axial alignment and impact receiving relation with the ring pin 45.

Before the hydrostatic piston has moved the booster and cam a distance suflicient to bring the two slider members together, the movable sleeve 24 will have moved to a position within the retaining sleeve 26 where the ball retaining aperture 2S will be in alignment with the annular pocket formed. by the projection 28. The hydrostat will then be immediately released from the stress applied by said compressed spring so that the slider members will be firmly brought together and the sub-booster transmission train I8 will be firmly pressed against the detonator M by the action of said booster extender mechanism. Release from the stress offered by the compressed spring 23 insures the positive action of said arming mechanism. Further movement Aoi" the booster extender mechanism causes the entire slider assembly to move the distance X against the action of the firing pin spring 46, compressing this spring and moving the firing pin retaining sleeve 48, together with the retaining block lil, into abutting relation with the partitioning member `5l which is held in its illustrated position by means of the cylinder 52.

The second hydrostat 53 includes a movable piston 53 adapted to be axially slidable Within the cylinder '52 and a Sylphon 54S which is sealed to said piston and to the end cap 55. The piston 53 has an elongated outwardly extending portion 5e which projects through an opening 5T formed in the end cap 55 and through a retaining collar 58. Movement of the hydrostat is opposed by the stress of the coiled ring pin spring and the natural resiliency of the Sylphon 54. One end of the spring i8 is positioned about the end of a flanged plug es recessed in the closed end of the extended portion of the piston 53, while the other end is positioned about a portion E2 of the firing pin d5 so as to press against a shoulder projecting therefrom.

A bushing 63 is secured to said piston `53 to provide a slidable surface for the firing pin sleeve 48. This bushing also forces the balls 6d which are retained in apertures 54 of the retaining sleeve A3 into the annular groove 65 formed in said firing pin A5, when the bushing covers said CII apertures, thus locking the firing pin to the re'- taining sleeve.

The outwardly extending portion 56 of said piston is also provided with a transverse bore 3l' through which is passed a suitable jump out pin 39 which bears against the retaining collar 5S to hold the piston in an immovable locked position so long as an arming wire similar to that shown at 'M in Fig. 4 holds the pin in place against the stress of a spring similar to that shown at 65. A baiiie 36 having vents similar to I9 in Fig. 4 is positioned over the end cap 55 so as to cover the fluid passages 68 communicating with the hydrostat 50.

In their secured or retained position the jump out pins prevent both the booster and ring pin extender mechanisms from moving axially in the body of the fuse as a result of inertia forces introduced as a result of the acceleration of the aircraft. The fuse is thus retained in a locked unarmed position. As soon as the arming wires are pulled free of the pins the springs 65 will force the pins outwardly of their position of locking engagement with the booster and firing pin extender mechanism, whereby each will be free to operate in response to hydrostatic pressure acting thereon.

In the construction illustrated in Figs. 1 to 4, inclusive, no means is provided for obtaining any adjustment of the depth at which said bomb will detonate, although an additional iiring pin spring Mi may be provided, as is indicated in Figs. 1 and 2 to increase the depth at which the iiring pin will be released to initiate the detonation of said bomb.

Figs. 5 and 6 illustrate a modification of a readily accessible combined locking and depth adjusting device, in which the firing pin TI is releasably secured to a retaining sleeve T8 by means of a plurality of balls Bil. The hydrostatic piston 'IS has an annular projection extending laterally inwardly therefrom forming a bushing 8i movable with said piston and slidable over the retaining sleeve so as to force the balls into the annular groove S2 formed in the firing pin '11.

Movement of said piston will cause the bushing to move relative to the retaining sleeve, compressing the firing pin spring 8d and releasing the iiring pin from the retaining sleeve when the apertures 83 are aligned with the shoulder formed by the enlarged portion of said annular projection.

A flanged stem 85 is threadably secured to the piston 'i9 through the threaded collar 3S which is keyed to the stem but movable axially thereof. A cup shaped member 37 provided with an integrally formed stud projecting rearwardly from the closed end thereof through a suitable opening formed in the end cap 88 is secured to the end cap by means of a nut 89. A portion of the inner surface of this cup is threaded about the collar 85, whereby the relative longitudinal position of said collar on the shaft 85 may be changed as a result of the rotation of the cup shaped member 3i about the flanged stem 85. A coil spring 9i is formed about this stem, one end of which is adapted to engage the collar 56 and the other end of which is adapted to engage the iiange 92, when the flange and stem are moved with the hydrostatic piston. A disc 93 is keyed to the cup so as to be rotatable therewith and has a spring influenced button 91% which ts into an opening 35 formed in the end cap 83, whereby the disc 93 and cup 81 are looked in a 75 set position.

f'Ilne' disc-e3 may-alsobefrotated' tol a'locked'iposition which is indicated at S on'thedrawin'gs. Whenl the cup -31 'andi-disc' e 3-farelrotated' tol a'po- *si-tionwherein the-#spring inil'u'enced button" 9d Iflits.into-the openings oppositeS of VvFig-6, la pair soi-fears se, which' extend'.morallyI of the lflange 192, iarefeach axially laligned with the-projectingends 'I off'the` diametrically opposed bolts Si so- -as lto *prevent any relative'lmovementibetween the cup IQS'Iar'id the flanged'stem Se." The cup is'immova- "Blasi-since' it is-secured to the bombl casing'fand -thehydrostatiel pistonl islse'cureo'l to -the stem 85 "and is' therefore immovable, consequently the hydrostat is locked. Other suitable markings fmay be provided on the outer surface of the disc A"to indicate various depthsettings.

When the bomb-is loaded cn a bombing rack "of an aircraft an arming wire 93 may be in- Csorted into an opening 9S formed in the end of the 'projecting-stem to hold the stem in its locked position after theadiustaole depth setting mech- --anism has been rotated to the selected depth po- --sition. Asi-he cup and annular lock are rotated about the stem t5 to the selected depth position "indicatedcn the end cap, the bolts 'i are moved I'out of'lalignment with the projecting learsV '9% oi the ange and the collar' 8% is moved along `the' stem, moving the 'spring 9! closer to the `iiange"92. Orr-penetration of the bomb in a liquid 'medium hydrostatic pressure will act upon the xhydrostatic piston lt, causing it to move axially along the body oi the fuse, compressing the coil fspring Si between the collar 8E' and the flange -`V532.*The hydrostatic pressure causing this movement is equivalent to the weight of a'column vof `liquid having a height equal to the depth of penetration of said bomb.

The voperation or the hydrostatic bomb fuse, the constructional details of which are illus- -trated in Figs. 1 to 4 inclusive, and decribed above, is as follows:

In a completely assembled bomb the jump cut pins 39 and 3Q are inserted into the openings 3i and 3l formed, respectively, in the proljecting portion of the bolt' 2! and the piston '51. These pins are retained in position against the action of theirsprings bymeans of a plurality oi cotter pins lf3, so tiat the bombv may be safely `handled or transported. `When the bomb is` inserted into the bomb rack: of 'an aircraft' the `arming wires "l5, are inserted into an opening forme@ each oi the jump out pins 3s andSS'. The cotter pins 3 are 'then v-.fithdrawn that as the be LbA s released the arming wires will be -withdrann from the pins @il and 39', leaving these pins free to' jump out of the'r position 'of holding engagement with the piston 3'! and `the bolt 2 l, The fuse is now unlocked and ready to function. upon the proper application of pressure to the firing pin and booster extender mechanism. Upon the penetra-tiener a fluid medium by said b "s, ie duid will enter into the 'rst hydrostats til andV es, respectively, by means of the ports i9, formed in the bailie plates, and in order' to equalize the pressure acting on each hydrostat tube d@ is provided which communicates with the entrance passages to each liydrostat As pressure builds up in the booster extender mechanism 2a, the hydraulic piston ll is fcaused to move inwardly of the casing l2 and carries with it the bolt 2i and movable sleeve 2st. Theilange 25 formed integrally with the sleeve @2G compressesthe spring 23 positioned between this flange and a flange 2l which is" formed 'in- *itegrally with-'theiretaining sleeve 26. When the ifballretaining aperturev l.'29- passes the shoulder iof vthel retaining-sleeve formed by the enlarged annular projection *28, the hydrostatic piston isimlmediately vunlocked from the spring sleeve 24 "and continues its movement in the sameV direc- Y'tionunopposed by the stress of the coil spring'23. Afhe's'trengthof the holding spring is preferably so proportion that the action of the booster ex- O rtender Zloccurs-at-a lesser pressure, represent- YingM a lesser depth,- than -is required tocause the 'ringpin extender mechanism to function in the manner hereinafter described.

Movement of the hydraulic piston Il causes a 5 corresponding movement of the booster container SI5-Lto which it--is attached. As the booster moves in an inward direction along the diametrical axis ltoward the firing pin, the conical shaped cam -member `3l causes the detonator slider l2 and the v-primer slider tomove together against the stress or the coiled springs 38. The detonator 4d is moved tothe center line of the fuse and into alignment with the lead-in I8 of the sub-booster ll. Further, the percussion primer lili is moved 5 `into impact receiving relation with the firing pin 5 andinto ignition conductive relationship with the detonator. Continued I'movement of -the booster container and cam member causes the --retaining yblock tl, together with'the primer and '-detonator sliders lll and t2, respectively, to lmove .the distance X against the stress olered by the firing pin spring i, whereupon the retaining `blockwill butt against the partition 5l. This movement causes the retaining sleeve 48 to move o5 axially in the bushing E3 moving the retaining -balls B towardthe shoulder thereof.

V Asthe pressure builds up in the second hydrostat-, the hydraulic piston 53 is caused to move, `and in so doing compresses the iiring pin spring o .46. The bushing 53, which is secured to the hydraulic piston 53, is moved along the ring pin sleeve 158 a distancev Y, whereupon the rim of the .hydraulic piston will butt against the stationary Vpartition 5I. It should be noted that relative 5 VYmovement between sleeve 48 and bushing E3 continues to move the retaining balls Si) toward the shoulder of the bushing 3, since the outer bushningimoves in one direction while the inner sleeve moves in the other direction as a result ofthe hydrostatic pressure acting upon each hydrostat. -When the relative movement between the sleeve Vll8 containing the ball lock' 6B and the bushing is equal to Z, as shown in Fig. l, the ball lock is released by the bushing and the ring pin 45 is Vdriven by the Y:iring pinsprings and it into the percussion primer fit. This action res the primer et which ignites the detonator and, through the lead-in it, sub-booster! 1 and booster "l, detonates the bomb.

. It should be noted that the distance Z is greater 'than either Vdistance X or Y but is less than the sum of X and Y so that both hydrostats must .combine in producing the required relative move- `Vment between the iiring pin sleeveand the bush- `'65 fing 'before the firing pin will'be-released, and since "ie1de`rs` the' operation of'the arming and ring mechanism more certain, and more positive, than the hydrostatic forces of the prior art. Furthermore, the structural features herein presented make the fuse respond to the predetermined depth setting with a greater degree of exactness than is obtainable in the prior art hydrostatic fuses and the safety provisions which are provided are far more reliable than those found in prior art.

Other modications and changes in the proportions and arrangement of the parts may be made by those skilled in the art without departing from the nature of the invention, within the scope of what is hereinafter claimed.

The invention described herein maybe manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

I claim:

l. In a depth bomb, a firing and arming mechanism comprising a boostercharge having an associated ignition train, a rst slider containing a percussion primerv and an ignition conductive passage leading therefrom, a second slider containing a detonator and an ignition conductive passage leading therefrom, said sliders being initially spaced from said booster ignition train, a ring pin, yieldable means retaining said first and second sliders in initial spaced relation so that the said ignition conductive passages are blocked and so that said percussion primer is out of alignment with said ring pin, means responsive to hydrostatic pressure for moving said booster charge to bring its said ignition train to- Ward said detonator and into an ignition conductive position relative thereto, and means responsive to the movement of said booster for moving said sliders against the action of said yieldable means to bring the ignition conductive passage of the detonator into alignment with the ignition conductive passage of said percussion primer and with the ignition train of the booster and to bring the percussion primer into an impact receiving position with reference to said ring pin, whereby y the ring mechanism will be armed only after the bomb has penetrated the water to a predetermined depth.

2. In a depth bomb, firing mechanism having an axially disposed firing pin, a first member having a percussion cap movable to a first position wherein said percussion cap is in axial alignment with said firing pin so that the percussion cap will be in an impact receiving relation therewith, a booster charge, a second member having a detonator movable to a first position wherein said detonator will be in ignition conductive relationship with said percussion cap and with said booster charge, yieldable means for retaining each of said movable members in a second position wherein said percussion cap is out of axial alignment with said firing pin so as to be incapable of receiving impact therefrom, and wherein said detonator is out of ignition conductive relation with the primer and booster ch arge, and means responsive to hydrostatic pressure for moving said rst and second members to their first-named position against the action of said yieldable means, whereby the ring mechanism will be armed only after said bomb has penetrated the water to a predetermined depth.

3. In a depth bomb, an arming mechanism comprising a body member, a ring pin axially disposed therein, a first movable member containing a percussion primer normally retained in a posiill) tion wherein said primer is out of axial alignment with said ring pin, a second movable member containing a detonator normally retained in a position out of ignition conductive relationship with said primer, a hydrostat for moving said rst and second member from their normally retained positions to a position wherein said primer will be axially aligned with the firing pin to receive the impact therefrom and said detonator will be in ignition conductive relation with the primer, yieldable means opposing the movement of said hydrostat, and means for releasing the hydrostat from the opposing effect of said yieldable means after said hydrostat has moved said rst and second movable member a predetermined amount in order to insure the positive action of said arming mechanism and to retain the bomb in its armed position after the bomb has penetrated the water to a predetermined depth.

4. In a depth bomb, a firing and arniing mechanism comprising a booster charge, a first movable member, an ignition initiating means positioned therein, a second movable member, an ignition transmitting means positioned therein, yieldable means retaining said members in an initial position wherein said ignition initiating means is inoperative and said ignition transmitting means is in a nonconductive position relative to said rst named means and said booster charge, and hydrostatic pressure responsive means for moving said members to a second position wherein said ignition initiating means is in an operative position and said ignition transmitting means is in ignition conductive relationship with said rst means and said booster charge.

5. In a depth bomb, a i'lring mechanism comprising a body adapted to extend diametrically of said bomb, a spring, a carrier member, a firing pin secured thereto, said carrier and ring pin being movable along the diametrical axis of said body and against the action of said spring, a retaining sleeve within which said carrier is movable, said retaining sleeve being also movable along said diametrical axis against the action of said spring but in a direction opposite said rstnamed direction, a primary hydrostat for moving said retaining sleeve a distance X relative to said carrier, a secondary hydrostat for moving said carrier a distance Y relative to said retaining sleeve, and means for releasing said firing pin from said carrier in response to a relative movement between said carrier and sleeve equivalent to the distance Z wherein Z is greater than either X or Y 4but less than X-l-Y.

6. In a hydrostatic fuse for a depth bomb of the type adapted to be secured to a bomb rack of an aircraft, having a body member, means movable therein to arm said fuse, means movable therein to initiate the ignition thereof after said fuse has been armed, a safety device comprising removable pins adapted to hold each of said separate means in a locked immovable position, a spring for each of said pins, and an arming wire for holding each pin in the position of locking engagement against the action of said spring means, one end of each arming wire being secured to said aircraft, whereby the pins will be automatically removed from their position of looking engagement upon the release of said bomb from said rack.

'7. In a bomb, a booster charge, an hydrostat movable a predetermined distance in response to a predetermined hydrostatic pressure, means for initiating the detonation of said booster charge, a safety device for preventing detonation of said booster charge by said first-named means, saidv safety device comprising a plurality Yof movable members, one of; which contains a percussion primer/andan ignition conductivepassage leading therefrom'andanother'of which contains an ignition transmitting` means forrconducting the.

ignitionv Afrom said primer to said booster .charge and a spring yieldably maintaining said members inan initial position', .wherein the ignition.

booster comprises aspring inuenced `ring pin, a retaining sleeve therefor, said pin being re leasably secured .to said retaining sleeve, a .bushing secured to said secondhydrostat-so as to be movable therewith, i said. ring, pin Iretaining.

sleeve being,slidablysupported in said movable bushing, means-for. releasing saiddpin asa result of a predetermined Vrelative movement between said. sleeve and bushing, and .means actuated by said irsthydrostat for movingsaidsleeve relative to saidbushingafter said hydrostat has completed ,saidlinitial .partial movement actuating saidlsafety device to permitsaid detonation.

9. -In a depth bomb the combination of a spring inuenced ringpin, a sleeve therefor, said ring pin being releasably secured .to said sleeve, a

hydrostaticpiston, abushing secured thereto so 5" as to be movable,therewith,:said ring pin retains a ing. sleeve being positioned within said bushing, a stemhavinga flange projecting radially` therefrom, said stem -being secured to saidhydrosta-tic Y piston solastoproject` outwardlyl therefrom, a

coiled spring. positioned within thefpath `of` movementz of vsaid: stem,i retaining means for. said spring,`Y angular adjusting .means e for changing f the position of said retaining, means tochange, the'positionof an end .of` said'spring relative to' saidiiiange, whereby themovement ofv said hydrostat'will be limited bythe adjusted .distance,.of.l said end of-said spring and said flangeand bygthe compression forceslth'ereof, andy means for .ref-. leasing said pin upon movement of said bushing. relative to saidsleeve.

10. In a depth bomb, a body member,..a ring, mechanism comprising a spring. influenced Yfiring pin, releasably secured .to a retaining sleeve ata, distance spaced .from itspercussion cap,.a hydro.-Ar static piston, .a bushing secured .theretosoastd be movable therewith surrounding said retainingX sleeve, said hydrostatic,pistonhavinga flanged stem projecting therefrom, a coiled springposie: tioned in the path of movement,ofsaid-angedf stem, angular adjustingmeans for..changingtheJ position ofsaid spring relativento. the iiangeoa said stern, whereby the compressive forces of said spring opposing movement. ofsaid hydrostat will be increased, and means yfor releasingsaidv,,pinl upon .movementnof said` bushing relative to said. sleeve.

11. The invention as defined in claim 10; wherein said angularadjustingI means has-an inwardly-1I depending lug andsaidangehas aradially extending ear, so that in-.one angular,1 position .'of. said adjusting means said. ear-.andsaidlugfrwill1 be in axial alignment to. lock .said hydrostaticA means.

HARRY H. MOORE.

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